3. Subject is diagnosed with acute ischemic stroke and presents to the health care facility at a time such that initiation of NTS procedure is feasible within 6 hours of the time of stroke onset. The time of stroke onset is defined as the time at which a change in the baseline neurological function occurred. If the time is not known (e.g., the subject awakens from sleep with new symptoms), the last time the patient was observed to be neurologically intact must be considered to be the time of onset.